The present invention relates to implantable devices and, more particularly to an implantable patch prosthesis having one or more cusps to improve competency of a heart valve.
Congenital heart abnormalities, in the absence of appropriate surgical treatment, often result in an extremely poor life expectancy and/or quality of life. One particular abnormality is commonly referred to tetralogy of Fallot, which causes anatomic variability in the pulmonary outflow tract and pulmonary arteries. Some anatomic variations stemming from tetralogy of Fallot appear at infancy, such as stenosis at the pulmonary annulus, which may be associated with hypoplasia of the main pulmonary artery. Such anatomic variations may cause severe hypoxemia. Other anatomic variations associated with tetralogy of Fallot may not manifest symptoms until later in childhood, which may include infundibular stenosis with mild or no stenosis at the pulmonary arteries or branch pulmonary arteries.
If tetralogy of Fallot is left untreated, the pulmonary artery system may not develop sufficiently to accommodate total cardiac output, which is due to closure of the ventricular septal defect. This often causes right ventricular failure and mortality resulting from low cardiac output.
Several surgical techniques have been developed to help repair obstructions of the right ventricular outflow tract (RVOT), such as may be associated with tetralogy of Fallot. These may include palliative procedures and total correction, depending on the particular circumstances associated with the patient""s condition. Though it is most common for total correction to be utilized.
Total correction usually is implemented during a repair procedure in which an incision is cut in the pulmonary artery extending to the muscular part of the heart. A patch of a biocompatible material (e.g., synthetic or natural tissue) patch is applied across the pulmonary outflow annulus to relieve outflow obstruction. Because the patch passes through the pulmonic valve, which was cut by the incision, however, the valve tends to become insufficient. This has become acceptable, as a stenotic valve is more deleterious to a patient""s health and cardiac condition than a regurgitating (e.g., insufficient) valve.
As this practice has continued for many years, studies have indicated that a negative impact associated with pulmonary insufficiency after repair of tetralogy of Fallot. It has also been determined that a competent pulmonic valve is important for the normal growth of a child and the normal function of the pulmonic valve is important.
In an effort to alleviate pulmonary insufficiency, some surgeons are utilizing a patch that has a pericardial cusp formed thereon as part of RVOT reconstruction. The cusp, which is usually formed during the surgical procedure by fixation of the pericardium in a glutaraldehyde solution, is provided to compensate for the damaged cusp(s). This approach is not completely satisfactory as the cusp typically does not last. More particularly, the cusp is not designed so as to assure competency of the pulmonic valve.
The present invention relates to a cardiac patch prosthesis having one or more cusps. The patch prosthesis includes at least one cusp extending from a length of an associated valve wall. An elongated sheet of biocompatible material is attached to the valve wall, such that a portion of the elongated sheet extends beyond an inflow end of the cusp. A measurement system may be employed to measure the size of a patient""s native cusp(s), which measurement may be utilized to select a patch prosthesis having an appropriately sized cusp.
The measurement system includes at least two sizing tools (the number corresponding to the number cusps of a heart valve being constructed). Each of the sizing tools has a generally spherical end portion insertable into and dimensioned to measure size of a cusp. The end portions of the sizing tools are configured to engage each other and form a composite structure having a generally circular cross-section having a predetermined diameter that provides an indication of the size of the heart valve being constructed from the patch prosthesis and the native cusp(s).